Ignition control



June 21, 1955 D. T. ROBERTS IGNITION CONTROL Filed Jan, 8, 1953 IN V ENTOR.

United States IGNITION CONTROL The object of this invention is toadvance the ignition of an internal combustion engine with: (a) the airflow through the venturi; (b) the air pressure at the upstream lip ofthe butterfly throttle. By this means the centrifugal weights are notneeded. One problem has arisen due to the re-introduction of thetwo-stage carburetor. When the second stage becomes operative, the sparkmust not become unduly retarded, because the secondary venturi robs airfrom the primary venturi.

In the figures:

Figure 1 shows diagramatically the preferred form of my invention whereonly a one-stage carburetor is involved.

Figure 2 is also a diagrammatic representation of a two-stage carburetorincorporating my invention.

Figure 3 shows an alternative construction for a onestage carburetor.

Figure 4 shows a modification applicable specifically to the first stageof the two-stage carburetor shown in Figure 2.

In Figure 1:

is the air entrance.

12 is the venturi.

14 is a restriction in the wall of the throat.

16 is a restriction in the walls of the mixture outlet 42 just a littleupstream of the upstream lip of throttle 18 when throttle 18 is closedto its idling position.

20 is the throat of a small booster venturi subjected to the flow of airfrom restriction 14 to restriction 16, and vice-versa.

22 is the pipe leading from venturi 20 to 24 which is an air chamber.

26 is a diaphragm connected to 28 a link which advances the throttle.

In Figure 2:

10 is again the primary air entrance.

12 is the primary venturi.

atent O 14 is the restricted opening in the wall of the throat 18 is theprimary throttle (manual).

16 is a restricted opening just upstream of the upstream lip of thethrottle 18 when in its idling position.

30 is the secondary air entrance.

32 is the secondary venturi.

34 is a restriction in the wall of the throat of 32.

36 is a second restricted opening in the wall of 32 and is used to keepthe secondary throttle 38 opening at the right moment after it hasstarted to open.

Throttle 38 is slightly offset so that manifold suction keeps thesecondary throttle 38 shut until it is time for it to open.

40 is a restricted opening in the Wall of the mixture outlet 42 of theprimary stage of the carburetor, and becomes operative when the throttleis somewhere between 40 and 70, preferably to the horizontal.

44 is a common passage from restriction 36 and 40 and leading to an airchamber 46.

48 is a diaphragm connected to a link 50 which opens the secondarythrottle 38 when the suction in air chamber 46 is powerful enough toovercome the manifold suction in manifold 52, which tends to hold thesecondary throttle 38 shut.

This is the subject of a co-pending patent application Serial No.330,328, filed January 8, 1953 by Marion L. Smitley and Melvin F.Sterner jointly.

Resuming the description of my own invention:

54 is a check valve raised by the suction in the opening 34.

Below the valve 54 is a restricted passage 16.

60 is a booster venturi corresponding to booster venturi 20 of Figure 1.

62 is a passage from the throat of this booster venturi 60 to an airchamber 64 which has a diaphragm 66 connected to a link 68 whichadvances a circuit breaker '70 in a well-known manner.

In Figure 3 (the single stage):

10 is the air entrance.

18 is the throttle.

The restriction in the walls of the mixture outlet 42 is at 77 just alittle upstream of the upstream lip of the butterfly throttle 18.

A booster venturi 76 (#68:0.031" diam.)

78 is a passage leading from the throat.

80 is a restriction (#74=0.0225 diam.)

77 is a restriction (#38=O.1015 diam.)

A second restriction 82 (#56=0.0465" diam.) bleeds air from theatmosphere past spring loaded check valve 84.

Passage 78 leads to a diaphragm chamber and the suction in 78 advancesthe spark.

In Figure 4:

In place of one opening 16, I substitute two openings 72 and 74.Otherwise, everything is the same as in Figure 2.

Figures 2 and 4:

Combining Figure 4 with Figure 2, the following dimensions have beenfound to be satisfactory:

72=#65 (0.035" diam.)

74=#46 (0.081" diam.)

14=#51 (0.067 diam.)

60=venturi throat=#47 (0.0785" diam.) 54= /s" nylon ball 34=#20 (0.161"diam.)

OPERATION Figure 1 By varying the three restrictions 14, 16 and 20, thespark advance characteristics can be varied to meet the customers mostexacting demands. At top speeds either an increase, a decrease or auniform spark advance can be obtained from part throttle advance whichadvances the spark to a more or less constant degree over a wide rangeof air flows.

passage 56 connected to the Figure 2 Immediately after the primarycarburetor throttle 18 has been manually opened the flow throughrestriction 16 and venturi 60 at first advances the spark by the elfectof the depression created in the venturi 60 which is transferred throughthe passage 62 to the chamber 64. When the opening reaches the one-halfthrottle position the passage 40 becomes operative so that throttle 38thereupon opens due to the suction in the chamber 46 which is derivedfrom the passage 44 and is transferred to the chamber 46. The opening ofthrottle 38 which thus takes place reduces the flow through the firstventuri 12 and transfers some of the fiow to the secondary venturi 32.The suction at the opening 16 thereupon falls but meanwhile the suctionat opening 34 increases, the ball Figure 3 The throttle 18 causes agreat advance at part throttle limited only by the check valve 84 andspring loading this valve. The net result is that the venturi 76replaces the two restrictions 14 and 16 of Figure l audits venturi 20.

F igure 4 The two restrictions 72 and 74. are substituted for onerestriction 16 of Figure 2. The advance of the spark is thus madegradually so that a fast idle for example, will not call for an undulyhigh spark. The sudden advances in ignition inherent in constructionsshown in Figures 1, 2 and 3 are not always desirable 'during the periodwhen first opening the primary throttle from its idle position. i

What I claim is:

1. An ignition control system for an'internaI combustion engine having acarburetor having an air entrance, a mixture outlet and a butterflythrottle in said mixture outlet, and a restriction in the wall of saidoutlet so located as to be subjected to the suction downstream of theupstream lip of said butterfly throttle the moment it is moved away fromits idle position, a passage leading to said restriction from theatmosphere, a booster venturi in said passage, an air chamber, a movingwall therein, a connection from said moving wall to advance the spark ofsaid engine, a connection from said chamber to the throat of saidbooster venturi.

2. In a device as set forth in claim 1 in which there striction in thewall of the venturi throat, a connection from said restriction to saidbooster venturi so that the booster venturi is connected on one sidewith the mixture outlet and on the other with the throat of saidcarburetor, which is its connection with the atmosphere.

3. An ignition control system for an internal combustion engine having atwo-stage carburetor comprising a first stage, which is normally inoperation, and a second stage which is automatically activated after thefirst throttte has been opened at least one-half way, comprising aventuri air entrance to each stage, a butterfly throttle in themixture'outlet from the first stage, a restriction in the wall of theprimary mixture outlet located so as to be subjected to the suctiondownstream of the upstream lip of said primary throttle the moment it isopened from its idling position, a venturi in the air entrance to thefirst stage, a restriction in the wall of the venturi, a common passageconnecting the two restrictions together, an air entrance to this commonpassage, a booster venturi therein, a second venturi in the air entranceto the second stage carburetor, a restriction in the wallzof the throatof said second stage venturi, a passage connecting said restrictionandsaid common passage, a check valve in said passage so that thesuction in the second stage venturi only becomes active when the suctionin the second stage venturi is greaterthan the suction in the commonpassage, an air chamber, a moving wall, a mechanical connection fromsaid moving wall to advance the time of the ignition, a pipe connectingthe air chamber with the throat of said booster venturi.

References Cited in the file of this patent UNITED STATES PATENTS

